The invention relates to a Vuilleumier heat pump, and particularly to a regenerator for a Vuilleumier heat pump.
In FIG. 1, a typical Vuilleumier heat pump is provided with a hot cylinder 100 and a cold cylinder 200 arranged at right angles to each other. The hot cylinder 100 comprises a hot chamber 101 and an intermediate temperature chamber 102 which are separated by a hot displacer or piston 110. Further, the hot cylinder 100 comprises a hot heat exchanger 120 which absorbs heat energy from a burner portion 300, an intermediate temperature level heat exchanger 130 which discharges heat energy to the outside, and a hot regenerator 140 which absorbs and discharges heat from or to the fluid which moves between the hot chamber 101 and the intermediate temperature chamber 102.
The cold cylinder 200 comprises a cold chamber 201 and an intermediate temperature chamber 202 which are separated by a cold displacer or piston 210. Further, the cold cylinder 200 comprises a cold heat exchanger 220 which absorbs heat energy, an intermediate temperature level heat exchanger 230 which discharges heat energy to the outside, and a cold regenerator 240 which absorbs and discharges heat from or to the fluid which moves between the cold chamber 201 and the intermediate temperature chamber 202.
The Vuilleumier heat pump having the above described construction starts its operation with the hot heat exchanger 120 heated by the burner 300. High pressure gas (e.g. Helium gas) fills each of two cylinders 100, 200 which are comprised of the four different chambers 101,102, 201 and 202. The hot displacer 110 and the cold displacer 210 are reciprocated in respective cylinders 100,200 in a predetermined phase. Each displacer pushes compressed gas from a warm region to a colder region through a regenerator. The gas is expanded isothermally in the colder region where it does work on the displacer and produces refrigeration. Upon a return stroke, each displacer returns the gas to the warmer region via the regenerator in which the gas absorbs heat.
FIG. 2 shows the hot regenerator 140 and the cold regenerator 240 employed in the prior art. The regenerators 140,240 have a metallic net 5 in the center thereof. The regenerators 140,240 absorb a part of the heat of the gas which is directed from the hot chamber 101 into the intermediate temperature chamber 102, and from the intermediate temperature chamber 202 into the cold chamber 201. When the directions of the fluid are reversed, the heat absorbed in the regenerators 140,240 is emitted to warm the fluid which flows through the regenerators 140,240.
However, the conventional regenerator has a leaking problem, in which the fluid leaks through the gap which is created between the inner surface 6 of the body of the regenerator and the side surface of the net. The leaked hot or cold fluid flows directly into the heat exchangers 120,130,220 and 230 without achieving fully the heat exchanging effect of the regenerators. That causes a decrease of the efficiency of the heat pump. That is, because the leaked fluid flows directly between the hot and cold chambers, whereby the temperature of the cold chamber is increased, and the temperature of the hot chamber is decreased. The typical regenerator is disclosed in Japanese Utility Model Laid Open No. 1988-120055.